(The Scientist, Vol:10, #6, p. 11, March 18, 1996)
One of my beloved grandmothers arrived in the United States as a penniless child. When I was a boy and showed her a good report card, she used to ask me with a smile: "If you're so smart, why aren't you rich?"
I didn't know enough then to explain that some people are out of the cash economy, and that some productive assets are not priced by markets in a way that reflects their value to people. In other forms, her question has taken on larger significance in recent exchanges between economists and ecologists.
In December 1995, I published a book called How Many People Can the Earth Support? (New York, W.W. Norton and Co.). There I wrote: "Human numbers currently exceed 5.7 billion and increase by roughly an additional 90 million people per year. . . . The Earth's human...